Dynamometer thermo-couple for explosion-engines.



'N. M. HOPKINS.

DYNAMOMETER THERMO-COUPLE FOR EXPLOSION ENGINES.

APPLICATION FILED JULY 28. 1908.

Patented Sept. 28, 1909.

3 SHEETS-SHEET 1.

l HJ@ wf N. M. HOPKINS.

DYNAMOMETEP. THERMO-COUPLE PoR EXPLOSION ENGINES.

APPLICATION FILED JULY 28. 1908.

Patented Sept. 28, 1909. 3 SHEETS-SHEET 2.

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mrmes,

N. M. HOPKINS.

DYNAMOMETEE THERMO-COUPLE EDR EXPLOSION ENGINES.

APPLICATION FILED JULY 28. 1908.

Patented Sept. 28, 1909.

3 SHEETS-SHEET 3.

W M M e A /A/ A ...i

Elf/77765665 N NEVIL MONROE HOPKINS, OF WASHINGTON, DISTRICT 0F CLUMBIA.

DYNAMOMETEB THERMO-COUPLE FOR EXPLOSION-ENGINES.

Specilcation of Letters Patent. t Patented Sept. Applicationled J'uly 28, 1908. Serial No. 445,823.

To all fww'm. 'it may concern:

Be it known that I, Nnvn. MONROE Hor- KINS, a citizen of the United States, residing at Washington, in the District of Columbia, have invented certain new and useful Improvements in Dynamometer Thermo- Cou les for Explosion-Engines, which the ollowing is a specification. f

Inmy United States Let ers Patent 903,090, granted November 3, 1908, I have described and claimed a dynamometer for explosion-enginesv comprising a heat-responsive device located'in the engine-cylinder or in proximity to the point of as-ignition, specicallya thermo-couple, an a dynamometric indicator, specifically va milli-volt meter arranged at a `convenient point and electrically connected to the thermo-couple.

The present invention comprises specific improvements in thermo-couples adapted for use' in the specified combinatlon. l

Referring to the accompanying drawings:

. Figures 1, 2 and 3 are respectively a slde `lain bushing has two elevation, a transverse vertical section, and a plan view, with the top removed, of one type of thermo-couple; Figs. 4 and 5 are respectively a transverse vertical section and a plan view, with thetopremoved, of a ttinfr similar to that shown in .thQPreceding gures, but containing both thermo-couple and a gas-ignition device; and Figs. 6, 7 and 8 are transverse vertical sections of three other t-jlrlpes offittings carrying thermo-couples o The device shown in Figs. 1, 2 and 3 comprises a meta1` body 1 having a threaded lower end 2 or other means for providing a gas-tight joint with the engine-cylinder. The body Vis bored-and counterbored to receive a bushing 3. of refractory .insulating material 'such as porcelain. f A gas-tight joint between the body and bushin is secured by asbestos washers 4, a threade ring 5 screwing into the upper end ofthe body 1 and bearing lon `.the upper4 washer. The porcearallel longitudinal holes 3 which receive c osely-iitting massive copper tubes 6, through which pass the Wires 7, 8., of thethermo-couple. 'These wires may consist. respectively of iron and German` silver, and are brazed `or otherwise secured together at their .adjacent lower ends to pro- Y vide the heat-receptive junction. Theirends may be inclosed y a co1lar9 toxprovlde a secure j joint. Gas-tight g joints'v between the copper tubes 46 and the porcelain bushing are secured by asbestos washers 10, compressed by nuts 11 threaded onthe ends of the tubes. The wires 7, 8 are longitudinally adjustable within the copper tubes, gas-tight joints between the wires and tubes being secured by stufiing-boxes 12 at their upper ends havinor compressible packings. The wires are a justed by sliding them through lthe tubes, after loosening the packings.

In order that various thermo-couples may bea-interchangeably' used with different millivolt meters havingidentical scales, it is necessary that these thermo-couples should be so constructed as to receive and dissipate precisely the same amount of heat from the explosionases. The amount ot'v heat recelved is ependent on the length of those portions of the wires 7, 8 projecting into the cylinder and exposed to the gases. The provision t'or the longitudinal,adjustment and predetermined extent of exp sure of the Wires enables all thermo-coup es to be quickly standardized. It is moreover vitally important that the rate of heat-dissipation from the. wires 7, 8 should be such as to maintain their junction at. a temperature below the ignition-point of the gas-mixture supplied to the engine. A portion of the heat received by the wires passes from the thick-walled copper tubes 6l laterally through the porcelain bushing 3 to the metal body 1 and thence to the en lne-cylinder. This outflow of heat throug theinsulat-ion may be suiiicient, and serviceabledevices have been builtin which the required low temperature of the junction is thus maintained. It is usually preferred, however, to provide sup,

\plemental heat-dissipating surfaces. In the present instrument, such surfaces are sup- 4plied by two semi-circular brass plates 13,'

14, having adjacent openings 15., 16 receiv- .j

surfaces of these plates'is exposed to the air,

whereby they are kept relatively cool. The free ends o the wires 7, 8 extend through` and are soldered to the insulated metal stemsy of binding-posts 20,- which receive the leads l placing the thermo-couple infele'ctrical con nection with the milli-volt' meter. These leads should consist of wires of the same metals, respectively, as those of the thermocouple, in order `that there may b e no seat of electromotive force at the bmdlng-posts, which in use are at a temperature higher than that or' the atmosphere. The upper ends of the copper tubes and their stuiingboxes are protected by a cap 21 having oppositely disposed lugs 22, clamped beneath nuts 23 of the binding-posts. This cap, if of meta-l, is separated from the brass plates 13, 14 by a layer of insulation 24.

The device shown in Figs. 4 and 5 is identical with that shown in Figs. l, 2, 3, except that.. the porcelain bushing 3 is provided with a third longitudinal opening 25, receiving a wire 26 which constitutes one spark-electrode and is electrically connected at its upper end, by a spring' 2T and bindingpost 2S, to the spark-coil or other source of electric current. This electrode-wire has a shoulder 29 seated against an asbestos washer 30.

upper end, between asbestos washers 33. 34.A

'lhese three washers provide gas-tight joints.

. The other spark-electrode is a wire projccting from the lower end of the body 1. A cap 21of vulcanized fiber or other insulating material incloses the upper ends of the Awires and insulating tubes.

Fig. 6 shows a modified construction in which the metal body 1b receives a shouldered metal bushing 36. The copper tubes are insulated from the metal bushing byv orcelain tubes 37, which, being relatively t in,

. permit the ready outflow of heat from the thermo-couple wires. Gas-tight joints are I provided by asbestos washers clamped betubes.

tween the ends of the porcelain tubes and nuts threaded on the ends of the copper Gas-tight joints between the metal bushing 36 and the body 1 are secured by asbestos washers compressed by a ring 3S threaded into the upper end of the body.

In the modified construction shown in Fig. 7, the copper tubes 6 are surrounded by insulating tubes 39, and a filling 40 of lead is cast into the body 1 and around the insulating tubes, entering an internal groove 41 in the body and external grooves 42 in the insulating tubes, thereby providing a support and gas-tight joint for the tubes. The tubes 39 are clamped between upper nuts 43 and asbestos washers and lower nuts 44, the nuts threaded on the opposite ends of the copper tubes 6.

Fig. 8 shows a modification in which the metal body 1d directly receives insulating tubes 45 containing the copper tubes 6. Gastight joints' are provided between the eiids of the tubes 45 and the body by asbestos washers compressed by nuts 46, 47 threaded on the upper and lowerA ends of the copper tubes 6;

The metal fittings shown iii Figs. 6, 7, 8, are designed to receive the same support; piece, insulation, binding-posts and cap as that shown in Figs. 1, 2, 3, the brass radiating-plates 13, 14 being optional.

I clailn: Y. 1. In combination, a support, thermocouple wires, and metal tubes within and insulated from said support and receiving said wires.

2.`In combination, a support, thermocouple wires, metal tubes within and insulated ironi said support and receiving said wires, and a heat-radiating plate secured to the upper end of each tube.

3. ln combination, a support, and thermocouple wires having their ends united to provide a heat-receptive junction, said wires being longitudinally adjustable in said support and exposing a variable length to the source of heat.

4. In combination, a metal body, and insulated thermo-couple wires having their ends united to provide a heat-receptive junction, said wires being longitudinally adjustable in said body and exposing a variable length to the source of heat.

5. In combination, a metal body, insulated thermo-couple wires having their ends united to provide a heat-receptive junction, said wires being longitudinally adjustable in said body and exposing a variable length to the source of heat, and stuiing-boxes receiving the outer ends ofsaid wires.

6. In combination, a support, thermocouple wires, metal tubes within and insulated from said support and having stuiingboxes receiving sai wires, and a heat-radi- 'ating plate secured to the upper end of each 7. In combination, a metal body, an insulating bushing in said body, having longitudinal openings, metal tubes in said openings, compressible washers, and nuts, on the ends of said tubes, and thermo-couple wires extending through said tubes.

8. In combination, a metal body, an insulating bushing in said body, having three longitudinal openings, thermo-couple wires extending through two of said openings, an insulating tube lseated in the third opening, and a spark electrode extending through said third opening and tube.

9. A thermo-couple,comprising wires having joined ends, and metal tubes closely fitting the wires, leaving the juncture exposed.

11. In combination, an insulating bushing In testimony Whereof,-1 afx my signature having longitudinal openings, metal tlllbes in presence of two Witnesses. l in said o eninvs, abutments on one enc of y each tubel,3 comnessble Washers between the NLVIL MONROE HOPIYXINS' 5 abutments and the ends of the tubes, nuts at Witnesses:

the other ends of the tubes, and thermo- EUGENE A. BYRNES, couple Wires extending through the tubes. Jos. H. BLACKWOOD. 

